Recall Correction
Incorrect information was reported for NHTSA recall 05V362000 issued by Monaco Coach Corporation, which appeared in the October 2005 issue (page 22). It was stated that the recall affected 22 2004 Monaco coaches. NHTSA has since updated the recall notice on its Web site to reflect corrected information indicating that the recall actually involves 1998 and 1999 Safari Renegade motorhomes that were built on Spartan chassis equipped with Detroit Diesel Series 40 engines. The number of motorhomes affected is 21.
FMC regrets this error.
Tire Talk Two
Q: After reading the tire story in the April 2005 issue (“Where The Rubber Meets The Road,” page 64), I am curious about lowering my “cold” tire pressure. By the way, how cold is cold? Although the term “cold” was mentioned, I couldn’t find it defined anywhere. I live where the morning temperature could be anywhere from the mid 40s in the winter to 120 degrees in the summer. I did find information that said for each 10-degree temperature change, the tire pressure would fluctuate 1 pound, but where do I start?
My coach is equipped with 24.5-inch rims and all six tires have the same cold rating. The axle weights allow me to inflate to 95 psi cold, which really softens the ride. I have had no success trying to inflate my tires using the brake air tanks, so I purchased a compact 2.5-horsepower, 125-psi air compressor that does the job nicely and weighs about 20 pounds.
Second question: Since less tire pressure softens the ride, will lowering the air bag ride height also soften the ride? My coach is a 1993 Monaco Crown Royale on an eight-bag Roadmaster chassis equipped with eight new Bilstein shocks.
Third: Is it possible to replace my original-equipment steering wheel with a new “Smartwheel” steering wheel with controls at my fingertips?
One last question: Why do I have to push the gear selector pads for my Allison transmission so hard when it’s cold?
Pete Freestone, F318976
Lake Havasu City, Arizona
A: First of all, using the term “cold” in relation to checking tire pressures really has less to do with a specific temperature and more to do with tire use. A “cold” tire is one that has not been driven on for a period of time and has been allowed to cool to the ambient temperature for wherever you are. When the tire is driven on, motion and friction heat the rubber. The air inside the tire also heats up, causing the pressure to rise. The term “cold” has always been assumed, which is why it’s seldom explained. Just make sure you check the pressure before moving the coach and you’ll be fine.
When adjusting tire pressure for “comfort,” great care must be taken to not lower the pressure below a safe and proper level for the weight being carried by the tire. We checked with a Monaco representative, and your coach originally was equipped with Bridgestone (now Bridgestone/Firestone) tires. You can look on the company’s Web site (www.trucktires.com) to get the proper pressure information. You also can get a tire pressure weight chart from Monaco Coach Corporation; or you can call Monaco’s toll-free technical service line at (877) 466-6226 and a representative will find the information for you.
The key point here is that you must know the weight that’s being carried by the tire. And the only way to be certain of that weight is to have the motorhome weighed after you’ve loaded it for normal use. There is no way around having the coach weighed. Do not guess or estimate the weight or pressure. If you no longer have Bridgestone tires or if you are contemplating a change, accurate tire pressure information can be obtained from the other tire companies and Monaco Coach Corporation. For absolute clarity, never run any tire below the minimum cold inflated pressure as listed on the appropriate pressure/weight table. Driving on under-inflated tires can lead to fast and uneven tread wear, improper handling, and excessive heat buildup, which could result in tire failure.
In regard to your second question, the Monaco representative notes that the rubber air bags installed on your coach have metal attaching plates folded into them at the top and bottom of each bag. Factory stock air bag height is 8 inches (plus or minus 1 inch) as measured from the top of the air bag attaching plate to the bottom of the air bag mounting plate. All eight bags have the same height measurement. During coach operation, the bags can extend to 12 inches or collapse to 4 inches. It is possible for you to increase or decrease your static ride height 1 inch on the Monaco Coach Corporation Roadmaster chassis. A small change in ride height (even 1/4-inch) makes a significant difference in ride feel.
Caution: If you choose to adjust the ride height valves yourself, use jack stands that are capable of holding 25,000 pounds or more to prevent an accidental lowering of the coach while you are under it. Professional mechanics use heavy-duty stands or wood blocking. Make sure you block the frame itself, not just the axle or suspension parts.
Lowering the bag height will make the ride stiffer. Increasing the bag height will soften the ride. The weight on the axle remains the same as you adjust the ride height up or down. Raising the coach increases the volume of the bags on that axle. That rise results in a softer spring rate, because there is a greater volume of air to support the same weight. The taller coach is operating at the same bag pressure you started with. That may sound a little confusing, and the rounded shape of the bag tends to muddy the issue even more. With adjustments within a tolerance of plus or minus 1 inch, the change to the volume does not increase or decrease the air bag pressure. Since the feeling you are trying to achieve is completely subjective, you may want to adjust the bags more than once to achieve that “perfect” ride, by both raising and lowering the air bag height. Remember, should you change the air bag pressure, and thus the ride height, this also may affect the alignment.
A “Smartwheel” and steering column can be installed, but the cost of a retrofit might be prohibitive. Another significant and negative issue is the potential reliability of a custom-designed, custom-wired, and “one off” custom-critical systems installation. Monaco Coach Corporation does not offer such a retrofit (nor does any manufacturer), so you would be dealing with service entities outside of factory guidance. While almost anything “can” be done, this may be one of those projects that it’s best to avoid.
The Allison transmission shifter will probably last a lifetime. However, the durable plastic that was used when your coach was built is indeed rigid, particularly when cold. The tiny little switches under the touch pad do not need to move far to activate, but when the overlaying plastic is cold, a firm push is required. The newer-style Allison touch pad is much softer and more responsive to the touch, no matter the temperature.
GM Parking Brake
Q: I have a 1997 Winnebago motorhome on a 1996 Chevrolet chassis. It has the automatic parking brake on the driveshaft, which worked great for 50,000 miles. Since then I have had two problems. First, it will not hold well. Even a small grade requires chocks to keep the coach from rolling. Second, it is eating brake shoes. My favorite service shop installed new shoes, and after a 500-mile round trip, I arrived home with no holding power. Of course, they asked whether I was driving with the brake on, but since they had just replaced the shoes before I left, I was extra cautious. As there is no reason to ever use the manual parking pedal, I cannot believe I left the brake on. I’d appreciate any suggestions as to why the brake won’t hold and why it is burning shoes. The shop seems to be in the dark as to a reason. They have assured me it is assembled and adjusted properly.
Ed Meredith, F235217
Pittsburgh, Pennsylvania
A: To find an answer to your problem, we consulted Workhorse Custom Chassis, which acquired Chevrolet’s chassis business in 1999. According to a Workhorse representative, the brake used in your motorhome should be similar to those used in 1999 Workhorse models. Here’s what that rep had to say in response to your question.
“The brake will hold if it is adjusted properly and has lining on the shoes. There are two adjustments. The first is the cable length at the actuator chamber. The other adjustment is at the prop shaft brake inside the drum on the rear of the transmission.
“The brake is designed to be so-called ‘fail safe.’ This means that with any failure, the brake will apply. This is necessary to meet DOT standards for parking brakes. You may have wiped out the lining due to an application of the brake for some failure. The most common failure is total loss of power to the control system. For example, if you turn off the key while going down the road, the brake will apply. A common cause for loss of power is a relay failure. This can be intermittent if the relay is corroded. I would replace the relay unless it has been done recently. The relay is located near the left side cylinder head on 1999 Workhorse Custom Chassis models. I am not sure where it is on the 1997 Chevy. The possibility of damaged wiring is almost limitless, so the system wiring harness should be checked.
“The brake is spring-applied by an actuator with a strong coil spring inside it. The spring pulls the cable and applies the brake. The brake is released when an electric-powered hydraulic pump provides pressure to a hydraulic cylinder to compress the spring and release the brake. Thus, other failure possibilities include problems at the pump, such that it does not release the brake. Check to make sure the electric/hydraulic motor runs and the brake releases and stays released when in the “neutral” position. If it slowly applies, this could mean there’s a fluid leak or check valve problem. You also should make sure the reservoir is filled with transmission fluid.
“Similar systems have been used on thousands of industry truck models and most dealers should have people familiar with how to repair and adjust the system.”